multiphase

i heared that multiphase can model free surface in open channel.i ,ean that choose two phase fluid(water and air)and let the programm to fill each element to recieve to air.and now you will have free surface model? can you tell me if it's right. thanks. and how can i get a fluent manual. thanks too. bye

I am also trying to model free surface flow in open channels, using a similar method, have you had any success? If so what boundary conditions have you used for inlet, outlet, interface between the water and air, and the boundary above the air??? PLEASE let me know. Mat